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A test kit for detecting cyanide levels in cassava has been developed in Australia to help Africans determine whether plants contain dangerous amounts of this naturally occurring poison. Cassava is an important staple crop in Africa, but each year...

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A test kit for detecting cyanide levels in cassava has been developed in Australia to help Africans determine whether plants contain dangerous amounts of this naturally occurring poison. Cassava is an important staple crop in Africa, but each year many young children die from cyanide poisoning and many more women and children have developed konzo, a paralysing condition of the legs. In the last decade, more than 10,000 people have been affected by this disease in Mozambique, Tanzania and Zaire. Cassava poisoning is particularly prevalent in East Africa, where crops do net receive the high rainfall of West Africa, which helps to leach the cyanide from the leaves. Sun drying the crop can help to reduce the levels by as much as 50%, but even this amount of residual cyanide can be dangerous.
The simple kits have been developed by a team of chemists led by Howard Bradbury at the Australian National University in Canberra. The kit works overnight after a small amount of cassava (100mg) has been mixed with a drop of water (1mm). The mixture is then placed on paper containing a cyanide-sensitive enzyme, linamarase. If the mixture contains cyanide, the enzyme slowly reacts to release hydrogen cyanide, which turns an indicator strip on the paper from orange to brown. The kit was trialled in Nampula district, Mozambique, last year where it was found that, although the average cyanide content in the cassava samples was only 50 ppm, other samples contained very dangerous levels of cyanide which were 20 times the WHO recommended level (200 ppm).
The development of the kit has been funded by the Australian Centre of International Agricultural Research, ACIAR, which will also provide the free distribution of kits to, developing countries. A second kit is currently being developed by Bradbury and his team for extracting the enzyme linamarase from cassava leaves. If the kits prove to be a success, they could then be made in Africa.
Australian Centre for International Agricultural Research
GPO Box 1571, Canberra, ACT 2601, AUSTRALIA